Anti-back-draft damper



P. R. JORDAN ANTI-BACK-DRAFT DAMPER Feb. 27, 1940.

2 Sheets-Sheet 1 Filed 001;. l, 1938 INVENTOR. 5704 1?. (fa/ am Feb. 27, 1940. p JORDAN 2,192,009

ANTI -BACK-DRAFT DAMPER Filed 001:. 1, 1938 2 Sheets-Sheet 2 INVENTOR 739m A. jam/m Patented Feb. 27, 1940 UNITED STATES PATENT OFFICE v 2,192,009

ANTI-BACK-DRAFT DAMPER. Paul R. Jordan, Indianapolis, Ind. I Application October 1,1938, Serial No. 232,768

3 Claims.

of air when a number of flues are used to exhaust the air from a single room or group of connecting rooms.

One object of the present invention is to provide a back draft damper which can be installed in a flue with a minimum of time and expense.

Another object is to provide a back draft damper which may be installed in a flue already constructed without additional masonry work being required,

Another object of the invention is to provide an anti-back-draft damper which is economically manufactured and may be sold and installed at a low cost.

Another object of the invention is generally to improve the construction and functioning of antiback-draft dampers.

Other objects and features of the invention will be understood from the accompanying drawings and the following description and claims:

Fig. l is a sectional View of a flue having installed therein an anti-back-drait damper constructed in accordance with the invention. Fig. 2 is a perspective view of the stationary parts of the damper construction. Fig. 3 is a fragmentary view of a damper blade and associated parts. Fig. 4 isfanother view of the same taken in the direction indicated by the arrow 4 of Fig. 3. Fig.

5 is another view of the same taken in the direction of the arrow 5 of Fig. 3.

In the "drawings there is indicated a flue I which is assumed to be rectangular in shape and is provided with walls II and I2. The normal direction of air movement is upward as indicated by arrows I3. In Fig. 1 there is shown installed in said flue a preferred form of the invention which includes a stationary rectangular frame I4.

Said frame is preferably formed of angle irons, the lower legs I of the angles extending inwardly as shown in Fig. 2. The frame M has one dimension greater than the corresponding inside dimension of the flue and may thusbe placed in the angular position shown in Fig: 1 with the lower edgeresting upon a support I6 and the upper edge the bearing members 29.

resting against theopposite inner wall of the flue. 1 The support I 6 may be in the form of one or more bolts inset in the wall I I of the flue or a number of nails may be driven into the mortar joints of the flue for the same purpose. Other forms 5 of support may be used.

In conjunction with the frame M, there is provided a damper blade I"! preferably formed of sheet metal with an offset portion I8, an upwardly extending portionISand a downwardly 10 extending portion 20 of smaller area than the portion I9. The portions I9 and 2B lie in substantially parallel planes. A reinforcing angle 2| is secured to the rear surface of the portion I9 and extends over the major part of the portion Zil and is secured thereto by a spacer member 22. A counterweighting angle 23 is secured to the lower edge of the portion and serves approximately I to equalize the moments of inertia of the portions of the blade on either side of the offset I8.

Adjacent the edges .of the bladethere are provided bearing members 24 and 25 securedby bolts 26 to the offset portion I8 of the blade. Bearing member 25 carries a knife edge 21 extending beyond the edge of the blade. Bearing member 24 carries a knife edge notch 28. The frame I4 has securedon opposite sides thereof a pair of bearing members 29, each of which is provided with a hole, 30 for reception of the corre-v sponding bearing members 24 and 25. 30

A balancing rod 3| passes through a suitable opening in the offset portion I8 of the blade and is secured thereto by lock nuts 32.

In the assembly of the damper proper, the blade is first assembled without the bearing members 24 and 25. Said blade is then introduced into the frame l4 by means of openings 33 provided in the lower legs I5 at each side of the frame adjacent The bearing members it and 25 are each engaged with the corresponding bearing members 29 and are then secured to the blade by the bolts 25. The notch 28 prevents lateral movement of the blade. The frame I4 is then placed at an angle corresponding to that which it willassume in the flue and the adjusting rod3l is adjusted so that the blade I! will lie flat within the frame I4 when there is no difference of pressure on the opposite sides of the blade but will assume an upright position as shownin Fig. 1 when there is a slight excess of I pressure on the undersurface of the blade. In order to prevent noise of operation in the closing of the damper there is provided on the upper surface of the angle leg I5 above the bearing members 29, a strip 34 of felt or similar cushioning material. A similarstrip 35 is provided on the under surface of that portion of the leg l5 below the bearing member 29. It will be obvious that when the damper is closed, the upper portion l9 thereof engages the strip 34 and the lower portion 29 thereof engages the strip 35. A stop member 38 is secured to the frame I4 as best shown in Fig. 2 and serves to limit the opening of the damper.

The completely assembled damper construction may then be inserted in the flue and is usually passed upwardly therein beyond the support Hi. The frame I4 is then tilted to bring its lower edge against the support I6 and the opposite edge is brought to rest against the opposite wall of the flue. Thus, in the installation of the damper, no masonry work of any kind is required. Furthermore, no accurate sizing ofthe flue or the frame id is necessary since the angle of inclination is not critical within several degrees. The whole operation of placing the damper in the flue may be accomplished in a small fraction of a minute.

When onceinstalled, a loss of pressure in the ventilated room which might result in a down draft of air in the flue immediately results in the closing of the damper. A subsequent increase of the pressure acting on the larger area of the upper portion IQ of the damper blade serves to open the damper to its full open position against the stop 36. For equalizing the air flow through a number of related flues, the stop members 35 of their corresponding dampers may be suitably bent to adjust the full open positions of the individual dampers.

The provision of the adjusting rod Si in the position shown insures that it may easily be reached from below for further balancing of the blade if necessary. For this purpose, the lower end of. the rod 3| is provided with a slot 31 which may be engaged by a screw driver or other suitable tool.

The foregoing specification describes the inopening therein.

vention in one of its preferred forms of the details of which may be varied within wide limitsv by those skilled in the art without departing from the scope of the invention as defined in the appended claims.

The invention claimed is:

1. In combination with a flue, a damper frame I posite wall thereof, and a damper blade pivotally j mounted on said frame and adaptedto close said 2. In combination with a flue, a damper frame having .a draft opening therein, a support for an edge of said frame secured to a wall of said flue,

' said frame resting on said support and being inclined upwardly therefrom within said flue and having its opposite edge resting against the opposite wall thereof, a damper blade having por tions arranged in substantially parallel planes and an offset portion joining the same, a pair of detachable bearing members secured to said ofiset portion adjacent opposite edges of said blade, and mating bearingmembers carried by said frame and pivotally supporting said first mentioned bearing members. 4

3. In combination with a flue, a damper frame having a draft opening therein, a support for an edge of said frame secured to a wall of said flue,

said frame resting on said support and being in- V clined upwardly therefrom within said flue and having its opposite edge resting againstthe opposite wall thereof, a damper blade pivotally mounted on said frame and adapted to close said opening therein, and an-adjustab-le stop member attached to said frame and engaging said blade to define the limit of opening movement thereof.

PAUL RHJORDAN; 

